#include <stdio.h>
#include <stdlib.h>

typedef char ElementType;
typedef struct TNode *Position;
typedef Position BinTree;
struct TNode {
  ElementType Data;
  BinTree Left;
  BinTree Right;
};

BinTree CreatBinTree(); /* 实现细节忽略 */
void PreorderPrintLeaves(BinTree BT);

int main() {
  BinTree BT = CreatBinTree();
  printf("Leaf nodes are:");
  PreorderPrintLeaves(BT);
  printf("\n");

  return 0;
}
/* 你的代码将被嵌在这里 */
void PreorderPrintLeaves(BinTree BT) {
  if (NULL == BT) {
    return;
  }
  if (NULL == BT->Left && NULL == BT->Right) {
    printf(" %c", BT->Data);
  }
  PreorderPrintLeaves(BT->Left);
  PreorderPrintLeaves(BT->Right);
}
